Wanderlust kinetics and variable Ca(2+)-sensitivity of Drosophila, a large conductance Ca(2+)-activated K+ channel, expressed in oocytes.
Wanderlust kinetics and variable Ca(2+)-sensitivity of Drosophila, a large conductance Ca(2+)-activated K+ channel, expressed in oocytes.
复制标题
果蝇的游走动力学和可变 Ca(2) 敏感性，大电导 Ca(2) 激活 K 通道，在卵母细胞中表达。
DOI：
10.1016/s0006-3495(96)79833-8
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Magleby,KL
中科院分区：
文献类型：
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作者：
Silberberg,SD;Lagrutta,A;Adelman,JP;Magleby,KL
克隆的果蝇大电导钙激活钾通道（BK或maxi-K+通道）在非洲爪蟾卵母细胞中表达，并在离体膜上用膜片钳技术进行研究。一个天然的变体和一个突变体，消除了一个假定的环AMP依赖性蛋白激酶磷酸化位点表现出大，缓慢的波动，随着时间的推移开放的概率。这些波动，被称为“流浪癖动力学”，发生的时间过程为几十秒至几分钟，并具有与简单门控模型不一致的动力学特性。在5 mM咖啡因或50 nM毒胡萝卜素的存在下，或当通过添加5 mM HEDTA增加溶液的Ca 2+缓冲能力时，仍然观察到漫游癖动力学，这表明漫游癖动力学不是由切除的贴片中咖啡因和毒胡萝卜素敏感的内部储存的Ca 2+释放引起的。与旅游癖动力学相关的动力学的缓慢变化可以用离散状态马尔可夫模型产生，该模型具有三个或更多个具有不同水平的开放概率的动力学模式之间的转换。为了使漫游癖动力学平均化，分析了大量的数据，并证明了在从相同注射的mRNA表达的通道之间，开放概率为0.5所需的[Ca 2 +]i的高达三倍的差异。这些研究结果表明，克隆dSlo通道在切下的补丁从非洲爪蟾卵母细胞可以表现出很大的变异性门控特性，无论是在一个单一的通道和通道之间。
Cloned large conductance Ca(2+)-activated K+ channels (BK or maxi-K+ channels) from Drosophila (dSlo) were expressed in Xenopus oocytes and studied in excised membrane patches with the patch-clamp technique. Both a natural variant and a mutant that eliminated a putative cyclic AMP-dependent protein kinase phosphorylation site exhibited large, slow fluctuations in open probability with time. These fluctuations, termed "wanderlust kinetics," occurred with a time course of tens of seconds to minutes and had kinetic properties inconsistent with simple gating models. Wanderlust kinetics was still observed in the presence of 5 mM caffeine or 50 nM thapsigargin, or when the Ca2+ buffering capacity of the solution was increased by the addition of 5 mM HEDTA, suggesting that the wanderlust kinetics did not arise from Ca2+ release from caffeine and thapsigargin sensitive internal stores in the excised patch. The slow changes in kinetics associated with wanderlust kinetics could be generated with a discrete-state Markov model with transitions among three or more kinetic modes with different levels of open probability. To average out the wanderlust kinetics, large amounts of data were analyzed and demonstrated up to a threefold difference in the [Ca2+]i required for an open probability of 0.5 among channels expressed from the same injected mRNA. These findings indicate that cloned dSlo channels in excised patches from Xenopus oocytes can exhibit large variability in gating properties, both within a single channel and among channels.